New telecommunications services such as Internet access are being offered by phone companies. There is a growing demand for high speed Internet access, in addition to other new services such as digital television, which require special high speed connections from networks to residences. However, basic telecommunications services such as Plain Old Telephony service (POTs) are at present the main source of revenue for telephone companies. These services are typically provided from a telephone central office to the residences over twisted copper wire pairs which in some cases have been in place for many years, and in some cases have been recently upgraded.
The part of the telecommunications network that connects a telephone central office to the subscriber residences is known as the access network or the local loop. The local loop technology is still based primarily on the use of twisted wire pairs, but some optical fiber has been used to reach terminals for telephone service. To date there has been little deployment of high speed digital data services. When used herein, the term high speed data services refers to any type of digital data service including Internet access and digital video.
Access network equipment for telecommunications services must be able to support POTs services as well as being able to support new digital services which will eventually have high penetration rates.
A number of technologies for providing high speed digital data services have been explored and include wireless, Hybrid Fiber Coax (HFC), Fiber-to-the-Curb (FTTC), Fiber-to-the-Home (FTTH), Asymmetrical Digital Subscriber Line (ADSL) and Very high rate Digital Subscriber Line (VDSL).
A general conclusion is that although all of these technologies will play a role in phone companies' long term business objectives, the majority of today's upgradable narrowband deployment needs will best be met by switched wireline infrastrutures based on FTTC, ADSL, and VDSL technologies.
Because the service areas are all different in terms of the length and quality of the telephone wire between the telephone central office and the residences, the number and type of homes and their distance from the telephone central offices, no single technology or configuration of that technology will be optimized for all applications and all deployment scenarios. It can also be the case that a central office may be located in an area which has both urban and suburban characteristics (e.g. some old apartment buildings as well as new housing developments), so that a mixture of FTTC, ADSL, and VDSL technologies are required.
Present solutions to the problem of delivering signals over twisted wire pairs involve placing additional equipment in the telephone central office to transmit and receive high speed data signals, and to convert the high speed data signals from a packet based signal to a circuit based signal compatible with the Public Switched Telecommunications Network (PSTN).
Sometimes, because of the distance between the subscriber residence and the central office, the equipment for transmission and reception of high speed data signals over twisted wire pair must be placed remote from the central office, and closer to the subscriber residence. This can be accomplished by putting a device called a channel bank near an existing Remote Terminal (RT) which provides analog telephone service.
For transmission over the twisted wire pair, the analog telephone signal must be combined with the high speed data signal using a diplexor. At the residence, a diplexor is used to separate the signals again.
In the presently used configuration, numerous problems are encountered including the need to convert packet or cell based high speed data signals to frame based signals compatible with the public switched telephone network; the need to deploy additional racks of equipment in both the remote location and the central office to support the high speed data applications; the need to have separate computers to program the telephony equipment and high speed data equipment, and the need for external diplexors at the central office or remote terminal and the subscriber residence to combine the analog telephone signals with the high speed data signals and separate them back out again. In addition, there may be noise from the analog telephone signal which interferes with the high speed digital data signal.
There is the need for a system which can combine high speed data signals with digital telephony signals and generate a combined high speed data and analog telephone signal which can be transmitted over twisted wire pair from a terminal which can be located in the central office or remotely.
For these reasons it is necessary to have a flexible terminal which can be used in both the central office or in the field, and which can generate the analog telephone signal and high speed data signal on a single plug-in card. In addition, a means of transporting traditional voice signals combined with high speed data signals in the access network is required.